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Week of December 1, 2004 |
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Title: A comparison of the in vitro retentive strength of glass-ionomer cement, zinc-phosphate cement, and mineral trioxide aggregate for the retention of prefabricated posts in bovine incisors. Author: Vargas et al. Journal: JOE, 2004. Vol. 30 (11) p 775 Reviewer: Jonathan Lee, DDS Purpose: To compare the retentive strength of zinc-phosphate (ZP) cement, glass-ionomer (GI) cement, and mineral trioxide aggregate (MTA) in the retention of prefabricated posts. Materials & Methods: Sixty bovine incisors were disinfected and the crowns cut off with a diamond saw, leaving 20mm of root. The canals were instrumented to size 60 MAF and obturated with gutta-percha and Roth’s sealer using warm vertical technique. A 9mm post space was made using a #6 drill (Integral Post System) to allow #6 serrated parallel posts to fit passively. Canals were then rinsed with 17% EDTA and 5.25% NaOCl with saline in between. Samples were divided into 3 groups according to cement type: 1) ZP, 2) GI, and 3) MTA. Posts were cemented and allowed to set for 4 hours. Each root was mounted in a polymethacrylate block and stored in a humidor at 37˚C for 2 weeks. Then each specimen was tested for retention force (tensile force in an axial direction to produce failure of the cement) using the Instron Universal Testing Machine. Results: The mean retention force of the experimental materials were: ZP 0.376 ± 0.115, GI 0.362 ± 0.109, and MTA 0.182 ± 0.121. There was a significant difference between the retention force of MTA and both ZP and GI. Retention force of MTA was 52.6% less than ZP and 49.8% less than GI. Discussion: Currently there is no material advocated for use both to repair a root perforation and to cement a post. Even though MTA is an ideal perforation repair material, its retentive strength for posts is 50% less than other luting agents. |
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Title: Clinical management of a maxillary lateral incisor with vital pulp and type 3 dens invaginatus: a case report Author: Nallapati S Journal: Journal of Endodontics, Vol 30(10):726-731, 2004 Reviewer: Kevin Axx, DDS Purpose: Treatment of a maxillary right lateral incisor with a type 3 dens invaginatus and a large periapical lesion with vital pulp in a separate root canal. Materials & Methods: A healthy 24-year-old man presented to the author’s practice with a “gum boil above the upper right front tooth”. Clinical exam revealed an intraoral sinus tract in the labial gingiva adjacent to tooth #7. Pulp vitality determined and confirmed with cavity test. Radiograph showed enamel-lied tract mesially spanning the length of the tooth with a root canal separate from the main root canal system. Dx: healthy pulp with chronic apical periodontitis associated with type 3 dens invaginatus. Non-surgical endodontics was begun only on this separate root canal taking care not to disturb the main root canal system. A sero-sanguis discharge was seen on the first and second visits, after which Ca(OH)2 was placed and the tooth temporized. At the 3rd visit, more serous discharge was present, so surgical endodontics was performed utilizing an OptiBond composite retrofill and calcium sulfate in the crypt to aid in bone formation. Following the retrofill, the dens invaginatus root canal was obturated using sealer and Obtura, and a composite restoration placed.
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Title: Factors influencing defects of rotary nickel-titanium endodontic instruments after clinical use Author: Parashos et al. Journal: JOE, 30(10): 722. October 2004 Reviewer: Hung Do, DDS Purpose: To examine a large number of used, discarded rotary nickel-titanium (NiTi) instruments and to identify factors that may influence defects produced during clinical use. Materials &
Methods: · 7159 used NiTi rotary files were examined by one investigator · files were from 14 endodontists from 4 different countries · files were examined with the naked eye and then stereomicroscope at 10-45X magnification · data were collected and entered including: brand, length, size, taper, and # of uses · each instrument was rated in one of the following categories: 1. no defect 2. unwinding 3. torsional fracture- associated with unwinding defect 4. flexural fracture- not associated with unwinding defect · for the purposes of comparison these instruments were categorized according to their cross-sectional shape 1. S-shaped (Quantec, Quantec Flare) 2. Triple-U (GT, Orifice shapers, Profile) 3. Triangular fixed-taper (HERO, FlexMaster) 4. Triangular variable taper (ProTaper) · data summarized and statistically analyzed Results: · unwinding occurred in 12% of instruments · fractures occurred in 5% (1.5% torsional & 3.5% flexural) · these defects resulted in the instruments being discarded after 3-4 use. · Instruments w/o defects generally were discarded after 4-5th use · S-shaped files had the greatest defect, unwinding, and fracture compared to the other 3 types · The most important influence on defect rates was the operator, which may be related to clinical skill or a conscious decision to use instruments a specified number of times or until defects were evident
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Title: Levels of evidence for the outcome of endodontic retreatment Author: Paik S et al. Journal: JOE 30(11): 745-50, 2004 Reviewer: Aaron Doms, DDS Purpose: 1) To complete a thorough search of published literature related to clinical studies on the success and failure of non-surgical retreatment, and 2) to assign levels of evidence to these publications. Methods: Clinical studies related to success and failure of retreatment since 1970 were identified using both electronic and manual literature searches. For a study to be included in this review the inclusion criteria were as follows: a) short-term success and failure, b) long-term success and failure, c) success rate in a specified population, d) success rate using different materials and/or techniques, e) success rate of a unique case over time, f) comprehensive clinical review articles of success and failure. All selected articles were then examined to determine the level of evidence (LOE), see Table 2. The studies were also identified by type: randomized trial, cohort, case control, case series, and case report. Results: They found 37 publications that met the inclusion criteria. Table 3 shows the articles listed in alphabetical order with LOE and study type. There were no LOE 1 randomized control trials (high quality), as it is very difficult to set up randomized double-blinded well-controlled studies for endodontic retreatment. Thirteen case series LOE 4 articles are among the most highly quoted studies related to the success and failure of endodontic retreatment, and compromise 45% of the published literature related to non-surgical retreatment outcomes. But, these articles also create confusion regarding the predicted outcome of retreatment due to their varying modalities. Based on the results of this search, it appears that few high level studies have been published in the 34 years related to the success and failure of endodontic retreatment. |
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Title: Antimicrobial effect of ozonated water on bacteria invading dentinal tubules Author: Nagayoshi et al Journal: JOE Vol.30 No.11, P.778-781 Nov 2004 Reviewer: Alex Wang, DDS Purpose: To examine the effect of ozonated water against E. faecalis and S. mutans infections in vitro in bovine dentin, and to evaluate its cytotoxicity. Materials &
Methods: 1. E. faecalis and S. mutans were cultured in broth. Bovine incisors’ roots were cut into sliced blocks of 4mm thick. The canals were then inoculated with E. faecalis or S. mutans. 2. The canals of each specimen was irrigated by flushing for 10 min with the following solutions: 4mg/L of ozonated water, 4 mg/L of ozonated water with ultrasonication, distilled water, or distilled water with ultrasonication. One specimen was not irrigated as positive control and another was irrigated with 2.5% NaOCl as negative control. 3. The specimens were dried and the pulpal surface was scraped off and cultured. Colony-forming units (CFU) were counted. 4. To evaluate the invasion of bacteria into dentinal tubules, specimens were stained using a modified Gram-staining method. 5. To evaluate the permeability of bacterial cytoplasmic membrane, specimens were stained for fluorescence observations. 6. To evaluate the cytotoxicity of ozonated water, mouse fibroblasts were cultured in minimum essential medium and test solutions were added to the wells. Results: 1. The invasion of bacteria into dentinal tubules was confirmed by Gram-staining method. 2. The sample treated with ozonated water showed a significant decrease in the number of CFU of bacteria. 3. Fluorescence microscope analysis indicated an increase of membrane permeability of S. mutans when treated with ozonated water. 4. The number of CFU in specimens treated by ozonated water with sonication was almost as low as in those treated with 2.5% NaOCl. 5. Fibroblasts were significantly damaged by 2.5% NaOCl whereas there were no significant differences in the metabolic activity among saline, distilled water and ozonated water. Conclusion: Ozonated
water had nearly the same antimicrobial activity as 2.5% NaOCl
during irrigation, especially when combined with sonication.
Ozonated water also showed a low level of toxicity
against cultured cells. This might be useful for the root canal irrigation. |
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Week of December 15, 2004 |
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Title: Effect of 2% chlorhexidine gel as an intracanal medication on the apical seal of the root-canal system Author: Wuerch, Rolf and et.al Journal: JOE, Vol. 30, No. 11 (p788-791), Nov 2004. Reviewer: Brian S. Jeon, DMD Purpose: To evaluate the effect of 2% chlorhexidine gel on the seal when used as an intracanal medication for 14 days. Materials &
Methods: 1) 42 extracted, human, maxillary anterior with straight root canals were used. 2) The crowns were removed leaving a uniform 15mm root section. 3) The root canals were instrumented to working length (WL) using NiTi rotary files. 4) The teeth were divided into 3 groups of 14 teeth each: in group A, the canals were immediately obturated; in group B, calcium hydroxide paste was placed w/ lentulo-spiral; in group C, 2% chlorhexidine gel was placed into the canals using an Ultradent Capillary Tip. 5) After 14 days, the canals in groups B and C were obturated. In all groups, AH Plus sealer was used as an obturation sealer. 6) Using the method described by Ciucchi et al., each root was mounted on Plexiglas block and tested for microleakage using the Flodec device at 20cm H2O pressure. 7) A one-way ANOVA test, at p<0.05, was performed to compare the leakage. Results: The calcium hydroxide groups had higher leakage values than the other two groups, but none of the differences between the three groups was statistically significant. Discussion: Using 2% chlorhexidine gel as an intracanal medication for 2 wks does not adversely affect the apical seal when using AH Plus sealer. Many properties, including its effectiveness against E. faecalis and Candida albicans, and its low toxicity, make 2% chlorhexidine gel a suitable alternative to calcium hydroxide as in intracanal medication. |
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Title: Cervical root resorption
following bleaching of endodontically treated teeth Author: Madison et al. Journal: J Endodon.
16(12): 570. 1990. Reviewer: Dan Bitner, DMD Purpose: To examine the effects of various factors used in several bleaching techniques on the initiation of external root resorption in the animal model. Materials and Methods: 45 teeth from dogs were
used and assigned to the following groups:
The
Bleaching techniques included:
All
bleaching procedures were performed twice at a 1-week interval. There
was a 1-year observation period. Teeth
were extracted and the root surfaces were examined under the microscope. Results:
Discussion: Etching alone apparently is not responsible for the resorptive process, since resorption
was present in both the etched and unetched groups,
but was not observed in the teeth that were etched only and were not
bleached. From the results of this
study, heat plus 30% H202 was the combination
associated with resorption. |
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